1. Field of the Invention
The present invention pertains to a pipe pickup and laydown assembly for use on work sites, such as where a drilling rig, work over rig and/or snubbing unit is deployed. More particularly, the present invention pertains to a hydraulic powered, pipe pickup and laydown assembly for use in safely and efficiently delivering a tubular from a ground surface to a “V-door” of a drilling rig, or vice versa.
2. Brief Description of the Related Art
Drilling of oil and/or gas wells typically involves the drilling of a well bore to a desired depth in the earth's crust. At certain intervals, relatively large pipe—commonly referred to as “casing”—is installed into a well bore and cemented in place. Such casing, and/or a cement sheath surrounding the exterior surface of such casing, provides structural integrity to said well bore, while isolating formations penetrated by said well bore from each other. Additionally, after a well has been fully equipped with casing, production tubing can also be installed within said well bore (within the inner bore of said casing).
During pipe installation operations, casing, tubing or other pipe is typically inserted into a well bore in a number of separate sections of substantially equal length referred to as “joints.” The joints, which generally include threaded connections at both ends, are typically joined end-to-end at the earth's surface (typically from a drilling rig) in order to form a substantially continuous “string” of pipe that reaches downward into a well.
Such pipe sections—which can typically be from 20 to 40 feet or more in length, several inches in diameter, and weigh several thousand pounds—generally must be transferred from a pipe rack or other staging area to the rig floor of a drilling rig. Thus, transferring said pipe sections from said pipe rack to said rig floor in a safe and efficient manner can be a complex and time consuming task. In conventional pickup and laydown operations, a section of pipe or other tubular good is frequently lifted via a cable hoist; sometimes a tag line is attached to the pipe section in order to control the movement of the tubular good.
In some cases, pipe is transferred from a pipe rack or other staging area to a drilling rig using partially-automated pipe handling equipment. Such conventional pipe handling equipment, commonly referred to as pipe “laydown” or “pickup” machines, can often be used to convey individual pipe sections to the vicinity of a rig floor where a strap (attached to a hoisting means) may then be employed to lift such section vertically above the floor. However, such conventional pipe handling assemblies are relatively large and heavy; such devices require a large amount of space (which is often at a premium on drilling rigs and pipe racks), and may require multiple trucks to deliver, position and install such equipment. Further, such conventional pipe handling equipment can be expensive to manufacture and operate, and can be overdesigned for smaller, lighter weight tubular goods.
Thus, there is a need for a safe, efficient and easily controlled method and apparatus for delivering pipe and other tubular goods from a pipe rack or other staging area to an inlet opening (typically a so-called “V door”) of a drilling rig. The pipe transfer assembly should be relatively small and easy to transport, position and operate.